Conventionally, a known technique is an area reproduction technique that presents sound only to specified positions using a speaker array configured by disposing a plurality of speakers linearly, and thus presents different sounds to different positions in one space without interference. Use of this technique makes it possible to present reproduction sounds of different contents and different volumes to users.
Specifically, as disclosed in JP 2015-231087 A, a reproduction line that strengthens reproduction sounds and a non-reproduction line that weakens reproduction sounds are set on a control line which is parallel with a speaker array, and a control filter for radiating an audio beam of a predetermined sound pressure or more only to the set reproduction line is derived. A signal, which is obtained by convolving the signal of the reproduction sound with the derived control filter, is output from the speakers so that an audio beam is radiated only to the set reproduction line.
The above-described conventional technique has, however, a problem that an audio beam radiable range is limited by a length of the speaker array in a longitudinal direction.